title: Interaction and structure in polyelectrolyte/clay multilayers: a QCM-D study.
abstract: This study focuses on the investigation of the influence of the ionic strength on the internal structure, film forming behavior, and swelling properties of polyelectrolyte/clay multilayers. Layer-by-layer films were prepared with three different polyelectrolytes [polyethylenimine (PEI), polydiallyldimethylammoniumchloride (pDADMAC), and 2-hydroxy-3-trimethylammonium propyl chloride starch (HPMA starch)] in combination with laponite clay platelets on three different surfaces. All experiments were carried out at two different ionic strengths (30 mM or 500 mM NaCl). The experiments performed with strong polyelectrolytes revealed a higher film thickness and adsorbed masses of clay and polyelectrolyte at 500 mM NaCl. The films containing PEI showed different behavior and were considerably less sensitive to changes in the ionic strength. This was also reflected by the swelling behavior as demonstrated by quartz crystal microbalance with dissipation (QCM-D) measurements. Films comprising PEI showed, in contrast to the other polyelectrolytes, much lower swelling in water leading to more compact and stable films in humid environments which is important for numerous applications of LbL clay coatings.
authors.affiliation: Division of Surface and Interface Science, Institute of Chemistry, Karl-Franzens-University Graz, Heinrichstrasse 28, A-8010 Graz, Austria. gerald.findenig@gmail.com
authors.forename: Gerald
authors.initials: G
authors.lastname: Findenig
authors.forename: Rupert
authors.initials: R
authors.lastname: Kargl
authors.forename: Karin
authors.initials: K
authors.lastname: Stana-Kleinschek
authors.forename: Volker
authors.initials: V
authors.lastname: Ribitsch
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D000077215:Clay; D004573:Electrolytes / Q000737:chemistry; D015394:Molecular Structure; D009994:Osmolar Concentration; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D058525:Quartz Crystal Microbalance Techniques; D012965:Sodium Chloride / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D004573:Electrolytes; D011108:Polymers; D014867:Water; D012965:Sodium Chloride; D000077215:Clay